This invention relates to a bearing support or assembly and more particularly to an elastomeric bearing assembly which is adapted for use in supPorting marine propeller shafts which effectively supports the shaft in a wet running condition as well as in a dry slow running or starting condition. Elastomeric journal bearings have been found to be particularly suited for wet running conditions because of their exceptional ability to withstand the effects of corrosive fluids and to withstand the effects of abrasion from foreign materials which are carried in suspension in the sea water or other liquids in which the shaft and journal bearing assembly operates. Such elastomeric journal bearing assemblies have been made and are still being made with either rigid metallic support members or plastic support materials. A further advantage of the elastomeric journal bearings is that since they operate in a liquid medium they are self lubricated and therefore highly desirable for marine use as for the stern propeller shaft journals. One particular problem to the use of such elastomeric bearing assemblies has been the high coefficient of friction of dry rubber or elastomeric material during start up of rotation of the marine shaft. The attempts to solve this problem have been directed to pump water continuously to the bearing while rotating it continuously or to provide a new bearing assembly with movable parts to present different types of friction surfaces to the bearing shaft. In both instances, these measures increase the cost of operation or of producing the bearing assembly.
The present invention provides a new and improved elastomeric bearing assembly that utilizes a unique construction to permit the ease of starting the propeller shaft after a prolonged rest while simultaneously taking advantage of the unique properties of the rubber bearing surface under wet conditions to facilitate the support of the shaft and thus providing a very low coefficient of friction under either operating conditions. When rotating a metal shaft in a fluid lubricated bearing assembly, a pocket of fluid is formed at the lower portions of the supported shaft where the shaft comes into contact with spaced flat adjacent surfaces of the rubber surfaces. Such pockets of fluids when formed act as water wedges and raise the shaft from the elastomeric shaft interfaces and provide lubrication to the shaft. The present invention enhances the hydraulic fluid pocket while utilizing a low friction material upon which the propeller shaft can rest during start up. The unique structure enhances both features while retaining a cost effective structure and also reduces power consumption.